Which of the given option is NOT a factor in Union by Size?

(A) Maintain sizes (number of nodes) of all trees, and during union
(B) Make smaller tree, the subtree of the larger one
(C) Make the larger tree, the subtree of the smaller one
(D) Implementation: for each root node i, instead of setting parent[i] to -1, set it to -k if tree rooted at i has k nodes